Quenching apparatus for a high pressure synthesis gas process

ABSTRACT

A combined quenching and scrubbing structure for use in a synthesis gas process that employs high pressure and temperature. There is a thin walled quenching vessel that is constructed of high alloy steel to withstand the corrosive effects. It is contained inside of a low alloy steel spherical container that is thick walled to withstand the high pressure. An outlet from the quenching vessel has an orifice scrubber therein and both are located inside the spherical container.

[151 3,660,046 [451 May 2,1972

United States Patent Smith [54] QUENCHING APPARATUS FOR A HIGH PRESSURESYNTHESIS GAS PROCESS [72] Inventor: Randlow Smith, Houston, Tex.Assistant E iner-R. E. Sewin [73] Texaco Inc., New York, NY.

Feb. 5, 1970 AttorneyThomas H. Whaley and Carl G. Ries Assignee:

[57] ABSTRACT A combined quenching and scrubbing structure for use in a[22] Filed:

synthesis gas process that employs high pressure and temperature. Thereis a thin walled quenching vessel that is constructed of high alloysteel to withstand the corrosive effects. It is contained inside of alow alloy steel spherical container that is thick walled to withstandthe high pressure. An outlet from the quenching vessel has an orificescrubber therein and both are located inside the spherical container.

[ 56] References Cited UNITED STATES PATENTS 8 Claims, 1 Drawing Figure3,322,412 5/1967 Yurko et al............................26l/l28QUENCHING APPARATUS FOR A man PRESSURE SYNTHESIS GAS PROCESS BACKGROUNDOF THE INVENTION 1. Field of the Invention This invention relates toapparatus for use in chemical processes in general. More specifically,it concerns a particular combination of apparatus for use in connectionwith a high pressure synthesis gas process.

2. Description of the Prior Art In connection with hydrocarbon processessuch as one relating to synthesis gas generation whichincludes a partialoxidation unit, there has been an increase in the temperatures andpressures involved. The result has been that problems of corrosion havearisen. These pertain to conditions involving pressures above 600 poundsper square inch and particularly where the pressures are from 1,200 to3,500 pounds per square inch. Such conditions relate to the constructionof apparatus that is used for quenching the high temperature synthesisgas.

Attempts to control the corrosion problems by injection of aneutralizing agent such as ammonia were not satisfactory. It was foundthat raising the pH in the quench section had an adverse effect on thecarbon settling.

Another approach to the corrosion problems might have been the use ofalloys capable of withstanding low pHs. However, there are practicalproblems in cladding the heavy walled steel vessel that is involved.Furthermore, if the vessel were to be fabricated from such an alloy, itwould be practi cally prohibitive in cost due to the high pressuresinvolved. In addition, an object of the invention is to provide acombination that can eliminate some expensive piping and other equipmentthat was formerly used in the carbon scrubbing system.

SUMMARY OF THE INVENTION Briefly, the invention concerns a high pressuresynthesis gas process and includes apparatus for quenching saidsynthesis gas. It relates to the improvement which comprises incombination a thin walled quench vessel for receiving and quenching saidhigh pressure gas, and a thick walled container surrounding said quenchvessel and containing most of said high pressure therein. 1

Again briefly, the invention relates to a high pressure synthesis gasprocess wherein high temperatures in the range of about 1,800 to 3,500F. and high pressures of about 1,200 to 3,500 pounds per square inch areinvolved. Said process includes apparatus for quenching said synthesisgas. The invention concerns the improvement which comprises incombination a thin walled quench ,vessel for receiving and quenchingsaid synthesis gas, said quench vessel being constructed of a high alloysteel for withstanding said synthesis gas fluids having a pH in therange of about 3 to 9. The improvement also comprises a thick walledcontainer surrounding said quench vessel, said container being sphericaland being constructed of a low alloy steel selected for withstandingsubstantially all of said high pressure. The improvement additionallycomprises a gas outlet from said quench vessel, including a water'scrubber therein. The said outlet and scrubber are contained inside ofsaid container.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects andbenefits of the invention will be more fully set forth below inconnection with the best mode contemplated by the inventor of carryingout the invention, and in connection with which there are illustrationsprovided in the drawings, wherein:

The FIGURE of the drawing is a schematic illustration indicating thecombination of elements according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention relates to acombination of structural elements that are employed in a process suchas one for the production of synthesis gas from liquid hydrocarbons, byreaction with oxygen and steam. It includes a section known as a partialoxidation unit that includes a quench and carbon scrubbing section. Insuch a process the tendency has been to operate under increasedtemperatures and pressures so that the pressures may be as high as 2000pounds per square inch or more and the temperatures may be in the rangeof about 1,800 to 3,500 F. An example of such process is described inUS. Pat. No. 3,232,727 issued Feb. 1, 1966 to F. C. Guptill, Jr. et al.

Relevant aspects of the process relate to conditions that are obtainedat the' output of the synthesis gas generator. It involves quenching thehot synthesis gas to reduce its temperature rapidly. As this takes placethere is a removal of entrained carbon and the production of steam whichmay be useful in subsequent operations. Such carbon removal is partiallyaccomplished in the quench vessel where the hot gases are cooled in awater bath and the carbon that settles out is removed by drawing off thecarbon-in-water slurry to a nearby decanter. The hot gases are thentransmitted from the quench vessel, and remaining carbon is removed. Thelatter is ordinarily carried out in a number of steps that may includeadditional water scrubbing, etc., all of which has heretofore involvedexpensive piping.

In carrying out the foregoing process it has been found that the quenchvessel and the scrubbing system become practically prohibitive in costby'reason of the requirements for containing the high pressure andconcomitant corrosive conditions. Thus, in order to construct a quenchvessel that can withstand the corrosive effects under the pressureconditions imposed, the cost becomes quite uneconomical andthus notfeasible. However, by improving the structure according to thisinvention such difficulties are overcome.

An arrangement of apparatus according to the invention is schematicallyillustrated'in the drawing. There is a synthesis gas generator 11 thatfeeds the hot gases from the generator through an outlet pipe 12 into athin walled quench vessel 15. This quench'vessel 15 is'contained insideof a spherical thick walled container 16 in a pressure-tight manner.Thus, the high pressures of the hot gases that are coming from thegenerator 11 are contained within the container 16.

Container 16 is preferably constructed of steel having adequatethickness. However, it .need only have sufficient alloy constituents togive adequate life for relatively non-corrosive conditions, because thetemperature following the quenching action will be relatively low.

The quench vessel 15 is constructed with internal baffles (not shown)and other arrangement for causing the hot gases coming from thegenerator 11 to be quenched in a water bath 17. Such internal structureforms no part, per se, of the invention. A typical arrangement may belike that mentioned in the foregoing Guptill US. Pat. No. 3,232,727,i.e. quench apparatus as described in US. Pat. No. 2,896,927 to Nagleand Eastman. However, in accordance with this invention, the quenchvessel may be constructed using material of a minimum thickness becauseit need only withstand the differential pressure between the quenchvessel 15 and the container 16. Such differential pressure will be inthe order of twenty pounds per square inch.

Quench vessel 15 has a fluid flow line 20 that is connected at thebottom of the vessel 15 for drawing off the carbon-inwater slurry inbath 17, as indicated above.

Near the upper part of the vessel 15 there is an outlet conduit, or pipe22 that is entirely contained inside of the pressure container 16. Thisconduit 22 carries the output of synthesis gas from the quench vessel15, and it has an orifice scrubber 23 attached therein. The scrubber islocated near the outlet end thereof.

Scrubber 23 may be a conventional item which forms no part, 7

per se, of the invention; It removes additional entrained carbon fromthe cooledsynthesis gas, as the latter is discharged into the interiorof the container 16 above the level of a water bath 28 that ismaintained therein. There is a pipe 29 at the,

bottom of the container 16 which has a valve 30 connected thereto forcontrolling the removal of the water bath 28, as.

desired.

There is an entrainment eliminator 33 that is connected at the, outletfor the, synthesis gas from the container 16. Thereafter, there is aflow line 34 that is connected to the top of the entrainment element 33for carrying away the synthesis gas. Line 34 will lead. to the rest ofthe process, or if necessary, it will lead to a second stage of carbonscrubbing.

It will be particularly noted that the quench vessel may be constructedof thin walled material as has been pointed out above. The pressuredifferential between its interior and its exterior need, only be on theorder of pounds per square inch. This is becausethe outer pressurecontainer 16 is constructed of adequately thick material to withstandthe high pressure conditions in the process. Such pressure may beupwards of the range of 1,200 to 3,500 pounds per square inch. I

The quench vessel 15 is preferably constructed of high alloy steelsuchthat is can withstand the corrosive properties of synthesis gas fluidshaving a pH in the range of about 3 to 9. By reason of the low pressuredifferential, this high alloy steel may have a minimum thickness. Forthis reason, the cost thereof will be greatlyreduced.

While the geometric shape of the container 16 might be something otherthan spherical, it is preferred to employ the spherical shape becausethis provides optimum pressure strength. In other words, thethicknesscan be kept to about half that required if some other geometric shapeswere employed. For example, for a given pressure the thickness of acylindrical shape must be about twice that of a spherical shape.

It is to be expected that the choice of steel torbe usedfor thesphericalcontainer 16 might be in accordance with Nelsons curves. Inthis regard, the use of the outer container 16 enables the addition ofneutralizing agents with minimum adverse effects on carbon settling inthe decanter. Therefore, it is clear that the thick walled container maybe constructed of a low alloy steel which will reduce the cost of thecontainer to a minimum.

It will also be noted that by reason of having the quenchvesselcontained inside of the pressure container, there is sufficientinterior space to accommodate the orifice scrubber with a short anddirect connection to the outlet of the quench vessel. The result is theelimination ofa substantial amount of expensive piping and concomitantexpansion problems. Also, at

- least a substantial portion of formerly needed scrubbing ele- V mentsmay be'eliminated.

- While a particular embodiment of the invention has been describedabove in considerable detail in accordance with the applicable statutes,this is not to be taken as in any way limiting the invention but merelyas being descriptive thereof.

I claim: I 1. Apparatus for use in a high pressure synthesis gas processincluding apparatus for quenching said synthesis-gas, the improvementcomprising in combination an enclosed thin walled quench vessel forreceiving and quenching said high pressure gas, a gas outlet from saidquench vessel including a water scrubber therein, and a thick walledcontainer enclosing said gas outlet andvwater scrubber and said quenchvessel and containing most of said high pressure therein. 2. Theinvention according to claim 1 wherein said thin walled quench vessel isconstructed of a high corrosion resistant rnetal, and I wherein saidthick walled container 18 constructed of a low alloy steel.

3. The invention according to claim 2 wherein said thin walled quenchvessel is constructed of a high alloy steel for withstanding hightemperature fluids having a pH in the range of about 3 to 9. v

4. The invention according to claim 3 wherein said thick walledcontainer is spherical.

5. Apparatus for use in a high pressure synthesis gas process whereinhigh temperatures in the range of about 1,800" to 3,500 F. and highpressures of about l,200 to 3,500 pounds per square inch are involved,said process including apparatus for quenching said synthesis gas, theimprovement comprising in combination a thin walled quench vessel forreceiving and quenching said synthesis gas,

said quench vessel being constructed of a high alloy steel forwithstanding said synthesis gas fluids having a pH in the range of about3 to 9,

a thick walled container surrounding said quench vessel,

said container being spherical and being constructed of a low alloysteel selected for withstanding substantially all of said high pressure,and 1 a gas outlet from said quench vessel including a water scrubbertherein,

said outlet and scrubber being contained inside of said container.

6. The invention according to claim 1, further comprising means forsuspending said-thin walled quench vessel spaced from the-inside wallsof said thick walled container.

7. The invention according to claim 5, further comprising means forsuspending said thin walled quench vessel spaced from the inside wallsof said thick walled container.

8. The invention according to claim 7, wherein said thin walled quenchvessel is enclosed.

2. The invention according to claim 1 wherein said thin walled quenchvessel is constructed of a high corrosion resistant metal, and whereinsaid thick walled container is constructed of a low alloy steel.
 3. Theinvention according to claim 2 wherein said thin walled quench vessel isconstructed of a high alloy steel for withstanding high temperaturefluids having a pH in the range of about 3 to
 9. 4. The inventionaccording to claim 3 wherein said thick walled container is spherical.5. Apparatus for use in a high pressure synthesis gas process whereinhigh temperatures in the range of about 1,800* to 3,500* F. and highpressures of about 1,200 to 3,500 pounds per square inch are involved,said process including apparatus for quenching said synthesis gas, theimprovement comprising in combination a thin walled quench vessel forreceiving and quenching said synthesis gas, said quench vessel beingconstructed of a high alloy steel for withstanding said synthesis gasfluids having a pH in the range of about 3 to 9, a thick walledcontainer surrounding said quench vessel, said container being sphericaland being constructed of a low alloy steel selected for withstandingsubstantially all of said high pressure, and a gas outlet from saidquench vessel including a water scrubber therein, said outlet andscrubber being contained inside of said container.
 6. The inventionaccording to claim 1, further comprising means for suspending said thinwalled quench vessel spaced from the inside walls of said thick walledcontainer.
 7. The invention according to claim 5, further comprisingmeans for suspending said thin walled quench vessel spaced from theinside walls of said thick walled container.
 8. The invention accordingto claim 7, wherein said thin walled quench vessel is enclosed.